Electromechanical apparatus for producing artifical reverberation

ABSTRACT

In electromechanical apparatus, which includes a helical spring as a delay item for producing artificial reverberation, a movable element of a transducer is rigidly connected to at least one turn of the spring at a point intermediate the ends of the spring without interrupting its continuity. The movable element is a rotatable frame-wound coil and the connection is made between the spring and the sides of the coil disposed in parallel relationship with its axis of rotation. The portions of the turn or turns of the spring connected to the movable element are deformed inwardly toward the coil.

United States Patent Fidi et al. Mar. 14, 1972 1 VELE TR -M NICAL A AR U[s61 e r w w FOR PRODUCING ARTIFICAL UNITED STATES PATENTS REVERBERATIONl,852,795 4/1932 Wegel ..333/30 [72] Inventors: Werner Fidi, Baden;Franz Srb, Wien, 2, 7 1 0 C alla m t alboth of Austria 9 PrimaryExaminer-D. X. Sliney [22] Flled: Oct 1970 Attorney-John J. McGlew andAlfred E. Page [211 App]. No.: 79,995 [57] ABSTRACT In electromechanicalapparatus, which includes a helical [30] Foreign Appliuitlon PriorityData spring as a delay item for producing artificial reverberation, aOct. 22, 1969 Austria ..A 9967/69 Name element a isfigidly P' least oneturn of the spring at a point intermediate the ends of the springwithout interrupting its continuity. The movable US. Cl. "333/? R, 179/1J, 310/15 element is a rotatable frame wound coil and the connection is[51 1.

7/ 30 9 made between the spring and the sides of the coil disposed in[58] Field of Search ..3lQ/l5; 1 79/1 J; 333/30 R parallel relationshipwith its axis of rotation. The portions of the turn or turns of thespring connected to the movable element are deformed inwardly toward thecoil.

s Claims, 4 Drawing Figures PAIENTEUMAR 14 I912 3,649,933

I INVENTORS WERNER FIDI BY FRANZ SRB JQWMO W ATTORNEYSELECTROMECI-IANICAL APPARATUS FOR PRODUCING ARTIFICAL REVERBERATIONSUMMARY OF THE INVENTION The present invention is directed toelectromechanical apparatus including a helical spring which acts as adelay ele ment for producing artificial reverberation and, moreparticularly, it is directed to the use of electromechanical transducersincluding a movable element rigidly connected to the spring at the pointintermediate the ends of the spring. The transducers apply mechanicalvibrations to the spring and pick up the vibrations transmitting by thespring.

In a conventional form of electromechanical apparatus for producingartificial reverberation, an electromechanical transducer is disposed ateach end of the helical spring. In a more recent fonn of such apparatus,at least one transducer,

usually the pickup transducer, is not disposed at an end of the helicalspring but is located intermediate the ends of the spring. In this casethe continuity of the spring is interrupted by a movable element,usually a rotatable frame-wound .coil, of the transducer which iscoupled to the spring. It is essential for reliable functioning of sucha reverberation apparatus that no reflections, or only slightreflections, occur at the location at which the transducer is inserted,otherwise the desired live impression of the reverberation would bedisturbed.

Moreover, a good transmission of high frequency vibrations necessitatesthat the coupling between spring and the transducer is as close aspossible. It was hitherto not possible for these two requirements to beproperly satisfied. In addition to substantial mechanical difficulties,there were also undesirable and troublesome reflections becauseinterruption of the continuity of the helical spring, due to theintroduction of the movable element of the transducer between the endsof the spring, resulted in the creation of a type of junction whichdisturbed the smooth flow of torsional vibrations traversing the spring.

Therefore, it is essential to insure that the insertion of a transducerintermediate the ends of the spring results in the least possibledisturbance of the vibrations travelling through the spring. Inparticular, the degree of freedom of the individual modes of vibrationmust not be impaired by the introduction of the transducer, since thiscould, for example, convert the torsional vibrations into compressivevibrations. It is possible for transverse vibrations to occur inaddition to torsional vibrations and compressive vibrations, suchtransverse vibrations being capable of producing disturbance effects inthe same way as the compressive vibrations.

It is the primary object of the invention to provide an improvedapparatus for producing artificial reverberation, in which thedisadvantages of known apparatus are obviated or substantially reduced.

Accordingly, the present invention provides electromechanical apparatusfor producing artificial reverberation, including a helical spring whichfunctions as a delay element, and electromechanical transducers forapplying mechanical vibrations to the spring and for picking up thevibrations transmitted by the spring. In this apparatus at least one ofthe transducers is coupled to the spring intermediate the ends of thespring by a movable element of the transducer which is rigidly connectedto at least one turn of the spring without any interruption to thecontinuity of the spring at the connection.

Preferably, the movable element of the transducer coupled to the springintermediate the ends of the spring is a rotatable frame-wound coil.Conveniently, a connection between at least one turn of the spring andthe rotatable frame is made directly to a side of the frame which isparallel to the axis of rotation of the frame. The side of the frame maybe arranged inside or outside the turn or turns to which it isconnected. Advantageously, the connection is made by means of a hard,nonelastic adhesive.

In a preferred embodiment of the invention, each turn of the springconnected to the rotatable frame is deformed inwardly, so that the polarmoment of inertia of the deformed turn plus the rotatable frame is atleast approximately equal to that of turns not connected to therotatable frame-wound coil.

To insure that the stiffness of each inwardly deformed turn of thespring plus frame is equal to the stiffness of the undeformed turns ofthe spring, it is furthermore preferable that each deformed spring turnshould be provided with a reduced portion or notch which results in acorresponding reduction in its stiffness.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this disclosure. For a better understanding of the invention,its operating advantages and specific objects attained by its uses,reference should be had to the accompanying drawing and descriptivematter in which there are illustrated preferred embodiments of theinvention.

BRIEF DESCRIPTION OF THE DRAWING I DETAILED DESCRIPTION OF THE INVENTIONIn FIG. 1, a known reverberation apparatus is illustrated and isprovided with a helical spring S which is subdivided into two portionsS1 and S2. A rotatable frame-wound coil D2 of a pick up transducer ispositioned between the two axially spaced helical spring portions S1 andS2 in the magnetic field of a magnet system M2 having poles PN2, PS2. Aninput transducer, having a rotatable frame-wound coil D1, is disposedbetween the poles PNI, PS1 of a magnet system Ml, however, it is locatedat one end of the helical spring and the spring is supported at that endto the point A by the frame-wound coil D1 and a suspension F1, and it issupported at the other end to a fixed point B via the suspension F2.

It will be clear that, in the known apparatus of FIG. I, the mode ofconnection of the coil D2 results in a discontinuity in the helicalspring which gives rise to disturbance. To avoid such discontinuity, therotatable frame-sound coil D2 of the embodiment of the invention shownin FIG. 2, is positioned within the helical spring, one turn of thespring is rigidly connected at two oppositely disposed points 1 and 2 tothe two sides of the coil D2 which are parallel to the axis of rotationof the coil. The connection of the coil to the spring is effected byadhesive attachment and must be as rigid as possible to insure that theframe-wound coil is reliably driven by the vibrating spring turn.Accordingly, adhesives of an elastic nature should be avoided, and hard,nonelastic adhesives should be used. The magnet system M2 (not shown inFIG. 2) is arranged so that the spring, that is to say the part thereofsurrounding the frame-wound coil D2, is also disposed in the air gapbetween the poles PN2, PS2.

If the inwardly deformed portions of the spring turn, as illustrated inFIG. 2, are indented inwardly into contact with the two frame sides, thealternative embodiment illustrated in FIG. 3 may be used. In FIG. 3 thespring turn is deformed inwardly at two oppositely disposed positions,but instead of inserting the frame-wound coil D2 within the spring as inFIG. 2, the frame is applied over the spring turn so that the frame ispractically suspended on the spring turn. Similar to the arrangement inFIG. 2, in FIG. 3 the frame-wound coil D2 is attached to the spring turnat points 1 and 2 by means of rigid adhesive.

Where a particularly high sensitivity is required and less importance isattached to the transmission of high frequencies, it is advisable toconnect the frame-wound coil to more than one turn, for example with twospring turns, as shown in diagrammatic form in FIG. 4. In FIG. 4, theframe-wound coil D2 is adhesively attached to two adjacent turns of thespring at the four points 3, 4, 5 and 6.

It is preferable if each of the deformed turns is notched or providedwith reduced portions to insure that the stiffness of each deformed turnplus the frame attached to it is equal to the stiffness of theundeformed turns of the spring.

The question as to whether the frame is secured in accordance with FIG.2 or FIG. 3 is of no consequence for the end result. The choice ofeither of the two constructions for an individual case will thereforedepend only on manufacturing considerations.

In addition to providing the advantages already described, eachembodiment of the invention offers the further advantage of preventingany tensile forces of the spring from acting upon the frame anddeformation thereof is therefore obviated. Accordingly, a constructionof lighter weightmay be adopted.

In the description hereinabove, the invention has been described only inrelation to an electromechanical transducer having a rotatableframe-wound coil because, in addition to a high degree of efficiency,this construction provides for precise and controllable conditions. Theapparatus responds only to torsional vibrations, proportionally to thehomogeneity of the magnetic field and can also fundamentally employelectromechanical transducers which are provided with movable elementssuch as moving iron elements, moving magnets or the like.

What is claimed is: g

1. Electromechanical apparatus for producing artificial reverberation,comprising an elongated helical spring which operates as a delayelement, and electromechanical transducers for applying mechanicalvibrations to the springand for picking up the vibrations transmitted bythe spring, at least one of said transducers comprising a movableelement being rigidly connected to at least one turn of said helicalspring at a position intermediate the ends of the spring and without anyinterruption in the continuity of said spring at the connection forcoupling said transducer to said spring, said movable element of saidtransducer coupled to said spring intermediate the ends thereof being arotatable frame-wound coil, the connection between at least one turn ofsaid spring and said rotatable frame-wound coil being made directly to aside of the frame-wound coil which is disposed in parallel relationshipto the axis of rotation of said coil.

2. Electromechanical apparatus, as set forth in claim 1,

.wherein a hard, nonelastic adhesive being used for connecting saidframe-wound coil to the turn of said spring.

3. Apparatus, as set forth in claim 1, wherein said framewound coilbeing disposed within the turn of said spring to which it is connected.

4. Electromechanical apparatus, as set forth in claim 1, wherein saidframe-wound coil being disposed outside the turn of said spring to whichit is connected.

5. Electromechanical apparatus for producing artificial reverberation,comprising an elongated helical spring which operates as a delayelement, and electromechanical transducers for applying mechanicalvibrations to the spring and for picking up the vibrations transmittedby the spring, at least one of said transducers comprising a movableelement being rigidly connected to at least one turn of said helicalspring at a position intennediate the ends of the spring and without anyinterruption in the continuity of said spring at the connection forcoupling said transducer to said spring, said movable element of saidtransducer coupled to said spring intermediate the ends thereof being arotatable frame-wound coil, the portion of each turn of said springconnected to said rotatable frame-wound coil being deformed inwardlywhereby the polar moment of inertia of each said deformed turn plus saidrotatable frame-wound coil connected thereto is at least approximatelyequal to the polar moment of inertia of the remaining undeforrned turnsof said spring.

6. Electromechanical apparatus, as set forth in claim 5 wherein eachinwardly deformed turn of said spring being provided with reducedportions so that the stiffness of each said deformed turn plus saidframe-wound coil connected thereto IS equal to the stiffness of theremaining undefonned turns of said spring.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION.

3,649,933 Dated March 14, 1972 Patent No.

v Inventor(s) Werner Fidi, et 8.]. I

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

On the cover sheetjinser t '[73] Assignees! AKG Akustisc'he KinmGerKte IGesellschaft m.b.H. Signed and sealed this 7th day or November 1972.

(SEAL) Attest:

EDWARD I !.FLE'ICIII.-2R,JR. ROBERT GO'ITSCHALK Attesting Officer 7Commissioner of Patents PC4050 (10-69) USCOMM-DC scam-peg I 9 U.5.GOVERNMENT PRINTING OFFICE; [9'9 0-365334,

UNITED STATES PATENT OFFICE CETIFICATE 0F CORRECTION.

Patent No. 3,6h9,933 Dated March 1 4, 1972 Inventor(s) Werner Fidi, etal It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

On the cover sheet insert [73] Assignees-: AKG Akustische Kino-Ger'teGesellsohaft m.b.H.

Signed and sealed this 7th day of November 1972.,

(SEAL) Attest:

EDWARD M.FLETCHER,JR. Attesting Officer ROBERT GO'ITSCHALK Commissionerof Patents 3RM PC4050 USCOMM-DC 60376-P69 i U.S. GOVERNMENT FRINTlNGOFFICE 1 I959 Q-365'334

1. Electromechanical apparatus for producing artificial reverberation,comprising an elongated helical spring which operates as a delayelement, and electromechanical transducers for applying mechanicalvibrations to the spring and for picking up the vibrations transmittedby the spring, at least one of said transducers comprising a movableelement being rigidly connected to at least one turn of said helicalspring at a position intermediate the ends of the spring and without anyinterruption in the continuity of said spring at the connection forcoupling said transducer to said spring, said movable element of saidtransducer coupled to said spring intermediate the ends thereof being arotatable frame-wound coil, the connection between at least one turn ofsaid spring and said rotatable frame-wound coil being made directly to aside of the frame-wound coil which is disposed in parallel relationshipto the axis of rotation of said coil.
 2. Electromechanical apparatus, asset forth in claim 1, wherein a hard, nonelastic adhesive being used forconnecting said frame-wound coil to the turn of said spring. 3.Apparatus, as set forth in claim 1, wherein said frame-wound coil beingdisposed within the turn of said spring to which it is connected. 4.Electromechanical apparatus, as set forth in claim 1, wherein saidframe-wound coil being disposed outside the turn of said spring to whichit is connected.
 5. ElectromechanicaL apparatus for producing artificialreverberation, comprising an elongated helical spring which operates asa delay element, and electromechanical transducers for applyingmechanical vibrations to the spring and for picking up the vibrationstransmitted by the spring, at least one of said transducers comprising amovable element being rigidly connected to at least one turn of saidhelical spring at a position intermediate the ends of the spring andwithout any interruption in the continuity of said spring at theconnection for coupling said transducer to said spring, said movableelement of said transducer coupled to said spring intermediate the endsthereof being a rotatable frame-wound coil, the portion of each turn ofsaid spring connected to said rotatable frame-wound coil being deformedinwardly whereby the polar moment of inertia of each said deformed turnplus said rotatable frame-wound coil connected thereto is at leastapproximately equal to the polar moment of inertia of the remainingundeformed turns of said spring.
 6. Electromechanical apparatus, as setforth in claim 5 wherein each inwardly deformed turn of said springbeing provided with reduced portions so that the stiffness of each saiddeformed turn plus said frame-wound coil connected thereto is equal tothe stiffness of the remaining undeformed turns of said spring.